Help:Parser Functions

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Parser Functions are extensions to the MediaWiki software, mainly allowing IF statements. These supplement the "magic words", which are already present in MediaWiki. All the parser functions provided by this extension take the form:

This function evaluates a mathematical expression and returns the calculated value.

{{#expr: expression }}

The available operators are listed to the right, in order of precedence. See Help:Calculation for more details of the function of each operator. The accuracy and format of the result returned will vary depending on the operating system of the server running the wiki, and the number format of the site language.

When evaluating using boolean algebra, zero evaluates to false and any nonzero value, positive or negative, evaluates to true:

{{#expr: 1 and -1 }} → 1

{{#expr: 1 and 0 }} → 0

An empty input expression returns an empty string. Invalid expressions return one of several error messages, which can be caught using the #iferror function:

{{#expr: }} →

{{#expr: 1+ }} → Expression error: Missing operand for +.

{{#expr: 1 foo 2 }} → Expression error: Unrecognised word "foo".

Note, if using the output of magic words, you must raw format them in order to remove commas, and translate the numerals. For example {{NUMBEROFUSERS}} results in 11,058, where we want 11058 which can be obtained by {{formatnum:{{NUMBEROFUSERS}}|R}}. This is especially important in some languages, where numerals are translated. For example, in Bengali, {{NUMBEROFUSERS}} produces ৩০,০৬১.

#if

This function first tests whether the first parameter is not empty. If the first parameter is not empty the function displays the second argument. If the first parameter is empty or contains only whitespace characters (spaces, newlines, etc.) it displays the third argument.

{{#if: | yes | no}} → no

{{#if: string | yes | no}} → yes

{{#if: | yes | no}} → no

{{#if:

| yes | no}} → no

The test string is always interpreted as pure text, so mathematical expressions are not evaluated:

If the strings to be compared are given as equal calls to the same template containing such tags, then the condition is true, but in the case of two templates with identical content containing such tags it is false.

#iferror

This function takes an input string and returns one of two results; the function evaluates to true if the input string contains an HTML object with class="error", as generated by other parser functions such as #expr, #time and #rel2abs, template errors such as loops and recursions, and other "failsoft" parser errors.

{{#iferror: test string | value if error | value if correct }}

One or both of the return strings can be omitted. If the correct string is omitted, the test string is returned if it is not erroneous. If the error string is also omitted, an empty string is returned on an error:

except for an empty or wrong input expression (an error message is treated as an ordinary string; it is not equal to zero, so we get value if true).

Either or both the return values may be omitted; no output is given when the appropriate branch is left empty:

{{#ifexpr: 1 > 0 | yes }} → yes

{{#ifexpr: 1 < 0 | yes }} →

{{#ifexpr: 0 = 0 | yes }} → yes

{{#ifexpr: 1 > 0 | | no}} →

{{#ifexpr: 1 < 0 | | no}} → no

{{#ifexpr: 1 > 0 }} →

#ifexist

This function takes an input string, interprets it as a page title, and returns one of two values depending on whether or not the page exists on the local wiki.

{{#ifexist: page title | value if exists | value if doesn't exist }}

The function evaluates to true if the page exists, whether it contains content, is visibly blank (contains meta-data such as category links or magic words, but no visible content), is blank, or is a redirect. Only pages that are redlinked evaluate to false, including if the page used to exist but has been deleted.

#ifexist: is considered an "expensive parser function"; only a limited number of which can be included on any one page (including functions inside transcluded templates). When this limit is exceeded, the page is categorised into Category:Pages with too many expensive parser function calls, and any further #ifexist: functions automatically return false, whether the target page exists or not.

If a page checks a target using #ifexist:, then that page will appear in the Special:WhatLinksHere list for the target page. So if the code {{#ifexist:Foo}} were included live on this page (Help:Parser Functions), Special:WhatLinksHere/Foo will list Help:Parser Functions.

On wikis using a shared media repository, #ifexist: can be used to check if a file has been uploaded to the repository, but not to the wiki itself:

#time

¹ Requires PHP 5.1.0 and newer and rev:45208.
² This has the same value as Y, except that if the ISO week number (W) belongs to the previous or next year, that year is used instead.
³ Will output literal o if ¹ not fulfilled.

Month

n

Month index, not zero-padded.

3

m

Month index, zero-padded.

03

M

An abbreviation of the month name, in the site language.

Mar

F

The full month name in the site language.

March

xg

Output the full month name in the genitive form for site languages that distinguish between genitive and nominative forms.

For Polish:

(nominative)

{{#time:d F Y|20 June 2010}|pl}} → 20 czerwiec 2010

(genitive)

{{#time:d xg Y|20 June 2010|pl}} → 20 czerwca 2010

Week

W

ISO 8601 week number, zero-padded.

10

Day

j

Day of the month, not zero-padded.

3

d

Day of the month, zero-padded.

03

z

Day of the year (January 1 = 0).Template:Note To get the ISO day of the year add 1.

RFC 5322 formatted date, equivalent to D, j M Y H:i:s +0000, with weekday name and month name not internationalised.

Tue, 03 Mar 2015 20:35:41 +0000

Non-Gregorian calendars

Islamic

xmj

Day of the month.

12

xmF

Full month name.

Jumada al-awwal

xmn

Month index.

5

xmY

Full year.

1436

Iranian

xij

Day of the month.

12

xiF

Full month name.

Esfand

xin

Month index.

12

xiY

Full year.

1393

Hebrew

xjj

Day of the month.

12

xjF

Full month name.

Adar

xjt

Number of days in month.

29

xjx

Genitive form of the month name.

Adar

xjn

Month number.

6

xjY

Full year.

5775

Thai solar

xkY

Full year.

2558

Minguo/Juche year

xoY

Full year.

104

Japanese nengo

xtY

Full year.

平成27

Flags

xn

Format the next numeric code as a raw ASCII number.

In the Hindi language, {{#time:H, xnH}} produces ०६, 06.

xN

Like xn, but as a toggled flag, which endures until the end of the string or until the next appearance of xN in the string.

xr

Format the next number as a roman numeral. Only works for numbers up to 3000.

{{#time:xrY}} → MMXV

xh

Format the next number as a Hebrew numeral.

{{#time:xhY}} → ב'ט"ו

This parser function takes a date and/or time (in the Gregorian calendar) and formats it according to the syntax given. A date/time object can be specified; the default is the value of the magic word{{CURRENTTIMESTAMP}} – that is, the time the page was last rendered into HTML.

{{#time: format string }}

{{#time: format string | date/time object }}

{{#time: format string | date/time object | language code }}

The list of accepted formatting codes is given in the table to the right. Any character in the formatting string that is not recognised is passed through unaltered; this applies also to blank spaces (the system does not need them for interpreting the codes). There are also two ways to escape characters within the formatting string:

A backslash followed by a formatting character is interpreted as a single literal character

Characters enclosed in double quotes are considered literal characters, and the quotes are removed.

The range of acceptable input is 1 January 0111 → 31 December 9999. For the years 100 through 110 the output is inconsistent, Y and leap years are like the years 100-110, r, D, l and U are like interpreting these years as 2000-2010.

Year numbers 0-99 are interpreted as 2000-2069 and 1970-1999, even when written with leading zeros:{{#time: d F Y | 1 Jan 0069 }} → 01 January 0069

{{#time: d F Y | 1 Jan 0070 }} → 01 January 0070

The weekday is supplied for the years 100-110 and from 1753, for the years 111-1752 the r-output shows "Unknown" and the l-output "<>". As a consequence, the r-output is not accepted as input for these years.

Full or partial absolute dates can be specified; the function will "fill in" parts of the date that are not specified using the current values:

{{#time: Y | January 1 }} → 2015

Warning:

The fill-in feature is not consistent; some parts are filled in using the current values, others are not:

{{#time: Y m d H:i:s | June }} → 2015 06 03 00:00:00 Gives the start of the day, but the current day of the month and the current year.{{#time: Y m d H:i:s | 2003 }} → 2003 03 03 00:00:00 Gives the start of the day, but the current day of the year.

A six-digit number is interpreted as hours, minutes and seconds if possible, but otherwise as an error (not, for instance, a year and month):{{#time: Y m d H:i:s | 195909 }} → 2015 03 03 19:59:09 Input is treated as a time rather than a year+month code.{{#time: Y m d H:i:s | 196009 }} → Error: Invalid time.Although 19:60:09 is not a valid time, 196009 is not interpreted as September 1960.

The function performs a certain amount of date mathematics:

{{#time: d F Y | January 0 2008 }} → 31 December 2007

{{#time: d F | January 32 }} → Error: Invalid time.

{{#time: d F | February 29 2008 }} → 29 February

{{#time: d F | February 29 2007 }} → 01 March

{{#time:Y-F|now -1 months}} → 2015-February

The total length of the format strings of the calls of #time is limited to 6000 characters [1].

#timel

This function is identical to {{#time: ... }}, except that it uses the local time of the wiki (as set in $wgLocaltimezone) when no date is given.

{{#time: Y-m-d }} → 2015-03-03

{{#timel: Y-m-d }} → 2015-03-03

{{#time: Y F d h:i:s}} → 2015 March 03 08:35:41

{{#timel: Y F d h:i:s}} → 2015 March 03 08:35:41

#titleparts

This function separates a pagetitle into segments based on slashes, then returns some of those segments as output.

{{#titleparts: pagename | number of segments to return | first segment to return }}

If the number of segments parameter is not specified, it defaults to "0", which returns all the segments. If the first segment parameter is not specified or is "0", it defaults to "1":

{{#titleparts: Talk:Foo/bar/baz/quok }} → Talk:Foo/bar/baz/quok

{{#titleparts: Talk:Foo/bar/baz/quok | 1 }} → Talk:Foo

{{#titleparts: Talk:Foo/bar/baz/quok | 2 }} → Talk:Foo/bar

{{#titleparts: Talk:Foo/bar/baz/quok | 2 | 2 }} → bar/baz

{{#titleparts: Talk:Foo/bar/baz/quok | | 2 }} → bar/baz/quok

Negative values are accepted for both values. Negative values for number of segments effectively 'strips' segments from the end of the string. Negative values for first segment translates to "add this value to the total number of segments", loosely equivalent to "count from the right":

{{#titleparts: Talk:Foo/bar/baz/quok | -1 }} → Talk:Foo/bar/bazStrips one segment from the end of the string

{{#titleparts: Talk:Foo/bar/baz/quok | -4 }} → Strips all 4 segments from the end of the string

{{#titleparts: Talk:Foo/bar/baz/quok | -5 }} → Strips 5 segments from the end of the string (more than exist)

{{#titleparts: Talk:Foo/bar/baz/quok | | -1 }} → quok

{{#titleparts: Talk:Foo/bar/baz/quok | -1 | 2 }} → bar/bazStrips one segment from the end of the string, then returns the second segment and beyond

The string is split a maximum of 25 times; further slashes are ignored and the 25th element will contain the rest of the string. The string is also limited to 255 characters, as it is treated as a page title:

The results of substituted parser functions are undefined if the expressions contain unsubstituted volatile code such as variables or other parser functions. For consistent results, all the volatile code in the expression to be evaluated must be substituted. See Help:Substitution.

Tables

Currently wiki pipe table syntax doesn't work inside conditionals, but this can be worked around by using {{pipe}} to replace using | for the table syntax.

Parser functions will mangle wikitable syntax, treating all the raw pipe characters as parameter divisors. To avoid this, most wikis create the template Template:! with its contents only a raw pipe character (|). This 'hides' the pipe from the MediaWiki parser, ensuring that it is not considered until after all the templates and variables on a page have been expanded. Alternatively, raw HTML table syntax can be used, although this is less intuitive and more error-prone.

Stripping whitespace

Whitespace, including newlines, tabs, and spaces, is stripped from the beginning and end of all the parameters of these parser functions. If this is not desirable, comparison of strings can be done after putting them in quotation marks.